zig

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      1 // This file provides the system interface functions for Linux matching those
      2 // that are provided by libc, whether or not libc is linked. The following
      3 // abstractions are made:
      4 // * Work around kernel bugs and limitations. For example, see sendmmsg.
      5 // * Implement all the syscalls in the same way that libc functions will
      6 //   provide `rename` when only the `renameat` syscall exists.
      7 // * Does not support POSIX thread cancellation.
      8 const std = @import("../std.zig");
      9 const builtin = @import("builtin");
     10 const assert = std.debug.assert;
     11 const maxInt = std.math.maxInt;
     12 const elf = std.elf;
     13 const vdso = @import("linux/vdso.zig");
     14 const dl = @import("../dynamic_library.zig");
     15 
     16 pub usingnamespace switch (builtin.arch) {
     17     .i386 => @import("linux/i386.zig"),
     18     .x86_64 => @import("linux/x86_64.zig"),
     19     .aarch64 => @import("linux/arm64.zig"),
     20     .arm => @import("linux/arm-eabi.zig"),
     21     .riscv64 => @import("linux/riscv64.zig"),
     22     .mipsel => @import("linux/mipsel.zig"),
     23     else => struct {},
     24 };
     25 pub usingnamespace @import("bits.zig");
     26 pub const tls = @import("linux/tls.zig");
     27 
     28 /// Set by startup code, used by `getauxval`.
     29 pub var elf_aux_maybe: ?[*]std.elf.Auxv = null;
     30 
     31 /// See `std.elf` for the constants.
     32 pub fn getauxval(index: usize) usize {
     33     const auxv = elf_aux_maybe orelse return 0;
     34     var i: usize = 0;
     35     while (auxv[i].a_type != std.elf.AT_NULL) : (i += 1) {
     36         if (auxv[i].a_type == index)
     37             return auxv[i].a_un.a_val;
     38     }
     39     return 0;
     40 }
     41 
     42 /// Get the errno from a syscall return value, or 0 for no error.
     43 pub fn getErrno(r: usize) u12 {
     44     const signed_r = @bitCast(isize, r);
     45     return if (signed_r > -4096 and signed_r < 0) @intCast(u12, -signed_r) else 0;
     46 }
     47 
     48 pub fn dup2(old: i32, new: i32) usize {
     49     if (@hasDecl(@This(), "SYS_dup2")) {
     50         return syscall2(SYS_dup2, @bitCast(usize, @as(isize, old)), @bitCast(usize, @as(isize, new)));
     51     } else {
     52         if (old == new) {
     53             if (std.debug.runtime_safety) {
     54                 const rc = syscall2(SYS_fcntl, @bitCast(usize, @as(isize, old)), F_GETFD);
     55                 if (@bitCast(isize, rc) < 0) return rc;
     56             }
     57             return @intCast(usize, old);
     58         } else {
     59             return syscall3(SYS_dup3, @bitCast(usize, @as(isize, old)), @bitCast(usize, @as(isize, new)), 0);
     60         }
     61     }
     62 }
     63 
     64 pub fn dup3(old: i32, new: i32, flags: u32) usize {
     65     return syscall3(SYS_dup3, @bitCast(usize, @as(isize, old)), @bitCast(usize, @as(isize, new)), flags);
     66 }
     67 
     68 pub fn chdir(path: [*:0]const u8) usize {
     69     return syscall1(SYS_chdir, @ptrToInt(path));
     70 }
     71 
     72 pub fn chroot(path: [*:0]const u8) usize {
     73     return syscall1(SYS_chroot, @ptrToInt(path));
     74 }
     75 
     76 pub fn execve(path: [*:0]const u8, argv: [*:null]const ?[*:0]const u8, envp: [*:null]const ?[*:0]const u8) usize {
     77     return syscall3(SYS_execve, @ptrToInt(path), @ptrToInt(argv), @ptrToInt(envp));
     78 }
     79 
     80 pub fn fork() usize {
     81     if (@hasDecl(@This(), "SYS_fork")) {
     82         return syscall0(SYS_fork);
     83     } else {
     84         return syscall2(SYS_clone, SIGCHLD, 0);
     85     }
     86 }
     87 
     88 /// This must be inline, and inline call the syscall function, because if the
     89 /// child does a return it will clobber the parent's stack.
     90 /// It is advised to avoid this function and use clone instead, because
     91 /// the compiler is not aware of how vfork affects control flow and you may
     92 /// see different results in optimized builds.
     93 pub inline fn vfork() usize {
     94     return @call(.{ .modifier = .always_inline }, syscall0, .{SYS_vfork});
     95 }
     96 
     97 pub fn futimens(fd: i32, times: *const [2]timespec) usize {
     98     return utimensat(fd, null, times, 0);
     99 }
    100 
    101 pub fn utimensat(dirfd: i32, path: ?[*:0]const u8, times: *const [2]timespec, flags: u32) usize {
    102     return syscall4(SYS_utimensat, @bitCast(usize, @as(isize, dirfd)), @ptrToInt(path), @ptrToInt(times), flags);
    103 }
    104 
    105 pub fn futex_wait(uaddr: *const i32, futex_op: u32, val: i32, timeout: ?*timespec) usize {
    106     return syscall4(SYS_futex, @ptrToInt(uaddr), futex_op, @bitCast(u32, val), @ptrToInt(timeout));
    107 }
    108 
    109 pub fn futex_wake(uaddr: *const i32, futex_op: u32, val: i32) usize {
    110     return syscall3(SYS_futex, @ptrToInt(uaddr), futex_op, @bitCast(u32, val));
    111 }
    112 
    113 pub fn getcwd(buf: [*]u8, size: usize) usize {
    114     return syscall2(SYS_getcwd, @ptrToInt(buf), size);
    115 }
    116 
    117 pub fn getdents(fd: i32, dirp: [*]u8, len: usize) usize {
    118     return syscall3(
    119         SYS_getdents,
    120         @bitCast(usize, @as(isize, fd)),
    121         @ptrToInt(dirp),
    122         std.math.min(len, maxInt(c_int)),
    123     );
    124 }
    125 
    126 pub fn getdents64(fd: i32, dirp: [*]u8, len: usize) usize {
    127     return syscall3(
    128         SYS_getdents64,
    129         @bitCast(usize, @as(isize, fd)),
    130         @ptrToInt(dirp),
    131         std.math.min(len, maxInt(c_int)),
    132     );
    133 }
    134 
    135 pub fn inotify_init1(flags: u32) usize {
    136     return syscall1(SYS_inotify_init1, flags);
    137 }
    138 
    139 pub fn inotify_add_watch(fd: i32, pathname: [*:0]const u8, mask: u32) usize {
    140     return syscall3(SYS_inotify_add_watch, @bitCast(usize, @as(isize, fd)), @ptrToInt(pathname), mask);
    141 }
    142 
    143 pub fn inotify_rm_watch(fd: i32, wd: i32) usize {
    144     return syscall2(SYS_inotify_rm_watch, @bitCast(usize, @as(isize, fd)), @bitCast(usize, @as(isize, wd)));
    145 }
    146 
    147 pub fn readlink(noalias path: [*:0]const u8, noalias buf_ptr: [*]u8, buf_len: usize) usize {
    148     if (@hasDecl(@This(), "SYS_readlink")) {
    149         return syscall3(SYS_readlink, @ptrToInt(path), @ptrToInt(buf_ptr), buf_len);
    150     } else {
    151         return syscall4(SYS_readlinkat, @bitCast(usize, @as(isize, AT_FDCWD)), @ptrToInt(path), @ptrToInt(buf_ptr), buf_len);
    152     }
    153 }
    154 
    155 pub fn readlinkat(dirfd: i32, noalias path: [*:0]const u8, noalias buf_ptr: [*]u8, buf_len: usize) usize {
    156     return syscall4(SYS_readlinkat, @bitCast(usize, @as(isize, dirfd)), @ptrToInt(path), @ptrToInt(buf_ptr), buf_len);
    157 }
    158 
    159 pub fn mkdir(path: [*:0]const u8, mode: u32) usize {
    160     if (@hasDecl(@This(), "SYS_mkdir")) {
    161         return syscall2(SYS_mkdir, @ptrToInt(path), mode);
    162     } else {
    163         return syscall3(SYS_mkdirat, @bitCast(usize, @as(isize, AT_FDCWD)), @ptrToInt(path), mode);
    164     }
    165 }
    166 
    167 pub fn mkdirat(dirfd: i32, path: [*:0]const u8, mode: u32) usize {
    168     return syscall3(SYS_mkdirat, @bitCast(usize, @as(isize, dirfd)), @ptrToInt(path), mode);
    169 }
    170 
    171 pub fn mount(special: [*:0]const u8, dir: [*:0]const u8, fstype: [*:0]const u8, flags: u32, data: usize) usize {
    172     return syscall5(SYS_mount, @ptrToInt(special), @ptrToInt(dir), @ptrToInt(fstype), flags, data);
    173 }
    174 
    175 pub fn umount(special: [*:0]const u8) usize {
    176     return syscall2(SYS_umount2, @ptrToInt(special), 0);
    177 }
    178 
    179 pub fn umount2(special: [*:0]const u8, flags: u32) usize {
    180     return syscall2(SYS_umount2, @ptrToInt(special), flags);
    181 }
    182 
    183 pub fn mmap(address: ?[*]u8, length: usize, prot: usize, flags: u32, fd: i32, offset: u64) usize {
    184     if (@hasDecl(@This(), "SYS_mmap2")) {
    185         // Make sure the offset is also specified in multiples of page size
    186         if ((offset & (MMAP2_UNIT - 1)) != 0)
    187             return @bitCast(usize, @as(isize, -EINVAL));
    188 
    189         return syscall6(
    190             SYS_mmap2,
    191             @ptrToInt(address),
    192             length,
    193             prot,
    194             flags,
    195             @bitCast(usize, @as(isize, fd)),
    196             @truncate(usize, offset / MMAP2_UNIT),
    197         );
    198     } else {
    199         return syscall6(
    200             SYS_mmap,
    201             @ptrToInt(address),
    202             length,
    203             prot,
    204             flags,
    205             @bitCast(usize, @as(isize, fd)),
    206             offset,
    207         );
    208     }
    209 }
    210 
    211 pub fn mprotect(address: [*]const u8, length: usize, protection: usize) usize {
    212     return syscall3(SYS_mprotect, @ptrToInt(address), length, protection);
    213 }
    214 
    215 pub fn munmap(address: [*]const u8, length: usize) usize {
    216     return syscall2(SYS_munmap, @ptrToInt(address), length);
    217 }
    218 
    219 pub fn poll(fds: [*]pollfd, n: nfds_t, timeout: i32) usize {
    220     if (@hasDecl(@This(), "SYS_poll")) {
    221         return syscall3(SYS_poll, @ptrToInt(fds), n, @bitCast(u32, timeout));
    222     } else {
    223         return syscall6(
    224             SYS_ppoll,
    225             @ptrToInt(fds),
    226             n,
    227             @ptrToInt(if (timeout >= 0)
    228                 &timespec{
    229                     .tv_sec = @divTrunc(timeout, 1000),
    230                     .tv_nsec = @rem(timeout, 1000) * 1000000,
    231                 }
    232             else
    233                 null),
    234             0,
    235             0,
    236             NSIG / 8,
    237         );
    238     }
    239 }
    240 
    241 pub fn read(fd: i32, buf: [*]u8, count: usize) usize {
    242     return syscall3(SYS_read, @bitCast(usize, @as(isize, fd)), @ptrToInt(buf), count);
    243 }
    244 
    245 pub fn preadv(fd: i32, iov: [*]const iovec, count: usize, offset: u64) usize {
    246     return syscall5(
    247         SYS_preadv,
    248         @bitCast(usize, @as(isize, fd)),
    249         @ptrToInt(iov),
    250         count,
    251         @truncate(usize, offset),
    252         @truncate(usize, offset >> 32),
    253     );
    254 }
    255 
    256 pub fn preadv2(fd: i32, iov: [*]const iovec, count: usize, offset: u64, flags: kernel_rwf) usize {
    257     return syscall6(
    258         SYS_preadv2,
    259         @bitCast(usize, @as(isize, fd)),
    260         @ptrToInt(iov),
    261         count,
    262         @truncate(usize, offset),
    263         @truncate(usize, offset >> 32),
    264         flags,
    265     );
    266 }
    267 
    268 pub fn readv(fd: i32, iov: [*]const iovec, count: usize) usize {
    269     return syscall3(SYS_readv, @bitCast(usize, @as(isize, fd)), @ptrToInt(iov), count);
    270 }
    271 
    272 pub fn writev(fd: i32, iov: [*]const iovec_const, count: usize) usize {
    273     return syscall3(SYS_writev, @bitCast(usize, @as(isize, fd)), @ptrToInt(iov), count);
    274 }
    275 
    276 pub fn pwritev(fd: i32, iov: [*]const iovec_const, count: usize, offset: u64) usize {
    277     return syscall5(
    278         SYS_pwritev,
    279         @bitCast(usize, @as(isize, fd)),
    280         @ptrToInt(iov),
    281         count,
    282         @truncate(usize, offset),
    283         @truncate(usize, offset >> 32),
    284     );
    285 }
    286 
    287 pub fn pwritev2(fd: i32, iov: [*]const iovec_const, count: usize, offset: u64, flags: kernel_rwf) usize {
    288     return syscall6(
    289         SYS_pwritev2,
    290         @bitCast(usize, @as(isize, fd)),
    291         @ptrToInt(iov),
    292         count,
    293         @truncate(usize, offset),
    294         @truncate(usize, offset >> 32),
    295         flags,
    296     );
    297 }
    298 
    299 pub fn rmdir(path: [*:0]const u8) usize {
    300     if (@hasDecl(@This(), "SYS_rmdir")) {
    301         return syscall1(SYS_rmdir, @ptrToInt(path));
    302     } else {
    303         return syscall3(SYS_unlinkat, @bitCast(usize, @as(isize, AT_FDCWD)), @ptrToInt(path), AT_REMOVEDIR);
    304     }
    305 }
    306 
    307 pub fn symlink(existing: [*:0]const u8, new: [*:0]const u8) usize {
    308     if (@hasDecl(@This(), "SYS_symlink")) {
    309         return syscall2(SYS_symlink, @ptrToInt(existing), @ptrToInt(new));
    310     } else {
    311         return syscall3(SYS_symlinkat, @ptrToInt(existing), @bitCast(usize, @as(isize, AT_FDCWD)), @ptrToInt(new));
    312     }
    313 }
    314 
    315 pub fn symlinkat(existing: [*:0]const u8, newfd: i32, newpath: [*:0]const u8) usize {
    316     return syscall3(SYS_symlinkat, @ptrToInt(existing), @bitCast(usize, @as(isize, newfd)), @ptrToInt(newpath));
    317 }
    318 
    319 pub fn pread(fd: i32, buf: [*]u8, count: usize, offset: usize) usize {
    320     return syscall4(SYS_pread, @bitCast(usize, @as(isize, fd)), @ptrToInt(buf), count, offset);
    321 }
    322 
    323 pub fn access(path: [*:0]const u8, mode: u32) usize {
    324     if (@hasDecl(@This(), "SYS_access")) {
    325         return syscall2(SYS_access, @ptrToInt(path), mode);
    326     } else {
    327         return syscall4(SYS_faccessat, @bitCast(usize, @as(isize, AT_FDCWD)), @ptrToInt(path), mode, 0);
    328     }
    329 }
    330 
    331 pub fn faccessat(dirfd: i32, path: [*:0]const u8, mode: u32, flags: u32) usize {
    332     return syscall4(SYS_faccessat, @bitCast(usize, @as(isize, dirfd)), @ptrToInt(path), mode, flags);
    333 }
    334 
    335 pub fn pipe(fd: *[2]i32) usize {
    336     if (builtin.arch == .mipsel) {
    337         return syscall_pipe(fd);
    338     } else if (@hasDecl(@This(), "SYS_pipe")) {
    339         return syscall1(SYS_pipe, @ptrToInt(fd));
    340     } else {
    341         return syscall2(SYS_pipe2, @ptrToInt(fd), 0);
    342     }
    343 }
    344 
    345 pub fn pipe2(fd: *[2]i32, flags: u32) usize {
    346     return syscall2(SYS_pipe2, @ptrToInt(fd), flags);
    347 }
    348 
    349 pub fn write(fd: i32, buf: [*]const u8, count: usize) usize {
    350     return syscall3(SYS_write, @bitCast(usize, @as(isize, fd)), @ptrToInt(buf), count);
    351 }
    352 
    353 pub fn pwrite(fd: i32, buf: [*]const u8, count: usize, offset: usize) usize {
    354     return syscall4(SYS_pwrite, @bitCast(usize, @as(isize, fd)), @ptrToInt(buf), count, offset);
    355 }
    356 
    357 pub fn rename(old: [*:0]const u8, new: [*:0]const u8) usize {
    358     if (@hasDecl(@This(), "SYS_rename")) {
    359         return syscall2(SYS_rename, @ptrToInt(old), @ptrToInt(new));
    360     } else if (@hasDecl(@This(), "SYS_renameat")) {
    361         return syscall4(SYS_renameat, @bitCast(usize, @as(isize, AT_FDCWD)), @ptrToInt(old), @bitCast(usize, @as(isize, AT_FDCWD)), @ptrToInt(new));
    362     } else {
    363         return syscall5(SYS_renameat2, @bitCast(usize, @as(isize, AT_FDCWD)), @ptrToInt(old), @bitCast(usize, @as(isize, AT_FDCWD)), @ptrToInt(new), 0);
    364     }
    365 }
    366 
    367 pub fn renameat(oldfd: i32, oldpath: [*]const u8, newfd: i32, newpath: [*]const u8) usize {
    368     if (@hasDecl(@This(), "SYS_renameat")) {
    369         return syscall4(
    370             SYS_renameat,
    371             @bitCast(usize, @as(isize, oldfd)),
    372             @ptrToInt(old),
    373             @bitCast(usize, @as(isize, newfd)),
    374             @ptrToInt(new),
    375         );
    376     } else {
    377         return syscall5(
    378             SYS_renameat2,
    379             @bitCast(usize, @as(isize, oldfd)),
    380             @ptrToInt(old),
    381             @bitCast(usize, @as(isize, newfd)),
    382             @ptrToInt(new),
    383             0,
    384         );
    385     }
    386 }
    387 
    388 pub fn renameat2(oldfd: i32, oldpath: [*:0]const u8, newfd: i32, newpath: [*:0]const u8, flags: u32) usize {
    389     return syscall5(
    390         SYS_renameat2,
    391         @bitCast(usize, @as(isize, oldfd)),
    392         @ptrToInt(oldpath),
    393         @bitCast(usize, @as(isize, newfd)),
    394         @ptrToInt(newpath),
    395         flags,
    396     );
    397 }
    398 
    399 pub fn open(path: [*:0]const u8, flags: u32, perm: usize) usize {
    400     if (@hasDecl(@This(), "SYS_open")) {
    401         return syscall3(SYS_open, @ptrToInt(path), flags, perm);
    402     } else {
    403         return syscall4(
    404             SYS_openat,
    405             @bitCast(usize, @as(isize, AT_FDCWD)),
    406             @ptrToInt(path),
    407             flags,
    408             perm,
    409         );
    410     }
    411 }
    412 
    413 pub fn create(path: [*:0]const u8, perm: usize) usize {
    414     return syscall2(SYS_creat, @ptrToInt(path), perm);
    415 }
    416 
    417 pub fn openat(dirfd: i32, path: [*:0]const u8, flags: u32, mode: usize) usize {
    418     // dirfd could be negative, for example AT_FDCWD is -100
    419     return syscall4(SYS_openat, @bitCast(usize, @as(isize, dirfd)), @ptrToInt(path), flags, mode);
    420 }
    421 
    422 /// See also `clone` (from the arch-specific include)
    423 pub fn clone5(flags: usize, child_stack_ptr: usize, parent_tid: *i32, child_tid: *i32, newtls: usize) usize {
    424     return syscall5(SYS_clone, flags, child_stack_ptr, @ptrToInt(parent_tid), @ptrToInt(child_tid), newtls);
    425 }
    426 
    427 /// See also `clone` (from the arch-specific include)
    428 pub fn clone2(flags: u32, child_stack_ptr: usize) usize {
    429     return syscall2(SYS_clone, flags, child_stack_ptr);
    430 }
    431 
    432 pub fn close(fd: i32) usize {
    433     return syscall1(SYS_close, @bitCast(usize, @as(isize, fd)));
    434 }
    435 
    436 /// Can only be called on 32 bit systems. For 64 bit see `lseek`.
    437 pub fn llseek(fd: i32, offset: u64, result: ?*u64, whence: usize) usize {
    438     return syscall5(
    439         SYS__llseek,
    440         @bitCast(usize, @as(isize, fd)),
    441         @truncate(usize, offset >> 32),
    442         @truncate(usize, offset),
    443         @ptrToInt(result),
    444         whence,
    445     );
    446 }
    447 
    448 /// Can only be called on 64 bit systems. For 32 bit see `llseek`.
    449 pub fn lseek(fd: i32, offset: i64, whence: usize) usize {
    450     return syscall3(SYS_lseek, @bitCast(usize, @as(isize, fd)), @bitCast(usize, offset), whence);
    451 }
    452 
    453 pub fn exit(status: i32) noreturn {
    454     _ = syscall1(SYS_exit, @bitCast(usize, @as(isize, status)));
    455     unreachable;
    456 }
    457 
    458 pub fn exit_group(status: i32) noreturn {
    459     _ = syscall1(SYS_exit_group, @bitCast(usize, @as(isize, status)));
    460     unreachable;
    461 }
    462 
    463 pub fn getrandom(buf: [*]u8, count: usize, flags: u32) usize {
    464     return syscall3(SYS_getrandom, @ptrToInt(buf), count, flags);
    465 }
    466 
    467 pub fn kill(pid: pid_t, sig: i32) usize {
    468     return syscall2(SYS_kill, @bitCast(usize, @as(isize, pid)), @bitCast(usize, @as(isize, sig)));
    469 }
    470 
    471 pub fn tkill(tid: pid_t, sig: i32) usize {
    472     return syscall2(SYS_tkill, @bitCast(usize, @as(isize, tid)), @bitCast(usize, @as(isize, sig)));
    473 }
    474 
    475 pub fn tgkill(tgid: pid_t, tid: pid_t, sig: i32) usize {
    476     return syscall2(SYS_tgkill, @bitCast(usize, @as(isize, tgid)), @bitCast(usize, @as(isize, tid)), @bitCast(usize, @as(isize, sig)));
    477 }
    478 
    479 pub fn unlink(path: [*:0]const u8) usize {
    480     if (@hasDecl(@This(), "SYS_unlink")) {
    481         return syscall1(SYS_unlink, @ptrToInt(path));
    482     } else {
    483         return syscall3(SYS_unlinkat, @bitCast(usize, @as(isize, AT_FDCWD)), @ptrToInt(path), 0);
    484     }
    485 }
    486 
    487 pub fn unlinkat(dirfd: i32, path: [*:0]const u8, flags: u32) usize {
    488     return syscall3(SYS_unlinkat, @bitCast(usize, @as(isize, dirfd)), @ptrToInt(path), flags);
    489 }
    490 
    491 pub fn waitpid(pid: pid_t, status: *u32, flags: u32) usize {
    492     return syscall4(SYS_wait4, @bitCast(usize, @as(isize, pid)), @ptrToInt(status), flags, 0);
    493 }
    494 
    495 var vdso_clock_gettime = @ptrCast(?*const c_void, init_vdso_clock_gettime);
    496 
    497 // We must follow the C calling convention when we call into the VDSO
    498 const vdso_clock_gettime_ty = extern fn (i32, *timespec) usize;
    499 
    500 pub fn clock_gettime(clk_id: i32, tp: *timespec) usize {
    501     if (@hasDecl(@This(), "VDSO_CGT_SYM")) {
    502         const ptr = @atomicLoad(?*const c_void, &vdso_clock_gettime, .Unordered);
    503         if (ptr) |fn_ptr| {
    504             const f = @ptrCast(vdso_clock_gettime_ty, fn_ptr);
    505             const rc = f(clk_id, tp);
    506             switch (rc) {
    507                 0, @bitCast(usize, @as(isize, -EINVAL)) => return rc,
    508                 else => {},
    509             }
    510         }
    511     }
    512     return syscall2(SYS_clock_gettime, @bitCast(usize, @as(isize, clk_id)), @ptrToInt(tp));
    513 }
    514 
    515 extern fn init_vdso_clock_gettime(clk: i32, ts: *timespec) usize {
    516     const ptr = @intToPtr(?*const c_void, vdso.lookup(VDSO_CGT_VER, VDSO_CGT_SYM));
    517     // Note that we may not have a VDSO at all, update the stub address anyway
    518     // so that clock_gettime will fall back on the good old (and slow) syscall
    519     @atomicStore(?*const c_void, &vdso_clock_gettime, ptr, .Monotonic);
    520     // Call into the VDSO if available
    521     if (ptr) |fn_ptr| {
    522         const f = @ptrCast(vdso_clock_gettime_ty, fn_ptr);
    523         return f(clk, ts);
    524     }
    525     return @bitCast(usize, @as(isize, -ENOSYS));
    526 }
    527 
    528 pub fn clock_getres(clk_id: i32, tp: *timespec) usize {
    529     return syscall2(SYS_clock_getres, @bitCast(usize, @as(isize, clk_id)), @ptrToInt(tp));
    530 }
    531 
    532 pub fn clock_settime(clk_id: i32, tp: *const timespec) usize {
    533     return syscall2(SYS_clock_settime, @bitCast(usize, @as(isize, clk_id)), @ptrToInt(tp));
    534 }
    535 
    536 pub fn gettimeofday(tv: *timeval, tz: *timezone) usize {
    537     return syscall2(SYS_gettimeofday, @ptrToInt(tv), @ptrToInt(tz));
    538 }
    539 
    540 pub fn settimeofday(tv: *const timeval, tz: *const timezone) usize {
    541     return syscall2(SYS_settimeofday, @ptrToInt(tv), @ptrToInt(tz));
    542 }
    543 
    544 pub fn nanosleep(req: *const timespec, rem: ?*timespec) usize {
    545     return syscall2(SYS_nanosleep, @ptrToInt(req), @ptrToInt(rem));
    546 }
    547 
    548 pub fn setuid(uid: u32) usize {
    549     if (@hasDecl(@This(), "SYS_setuid32")) {
    550         return syscall1(SYS_setuid32, uid);
    551     } else {
    552         return syscall1(SYS_setuid, uid);
    553     }
    554 }
    555 
    556 pub fn setgid(gid: u32) usize {
    557     if (@hasDecl(@This(), "SYS_setgid32")) {
    558         return syscall1(SYS_setgid32, gid);
    559     } else {
    560         return syscall1(SYS_setgid, gid);
    561     }
    562 }
    563 
    564 pub fn setreuid(ruid: u32, euid: u32) usize {
    565     if (@hasDecl(@This(), "SYS_setreuid32")) {
    566         return syscall2(SYS_setreuid32, ruid, euid);
    567     } else {
    568         return syscall2(SYS_setreuid, ruid, euid);
    569     }
    570 }
    571 
    572 pub fn setregid(rgid: u32, egid: u32) usize {
    573     if (@hasDecl(@This(), "SYS_setregid32")) {
    574         return syscall2(SYS_setregid32, rgid, egid);
    575     } else {
    576         return syscall2(SYS_setregid, rgid, egid);
    577     }
    578 }
    579 
    580 pub fn getuid() u32 {
    581     if (@hasDecl(@This(), "SYS_getuid32")) {
    582         return @as(u32, syscall0(SYS_getuid32));
    583     } else {
    584         return @as(u32, syscall0(SYS_getuid));
    585     }
    586 }
    587 
    588 pub fn getgid() u32 {
    589     if (@hasDecl(@This(), "SYS_getgid32")) {
    590         return @as(u32, syscall0(SYS_getgid32));
    591     } else {
    592         return @as(u32, syscall0(SYS_getgid));
    593     }
    594 }
    595 
    596 pub fn geteuid() u32 {
    597     if (@hasDecl(@This(), "SYS_geteuid32")) {
    598         return @as(u32, syscall0(SYS_geteuid32));
    599     } else {
    600         return @as(u32, syscall0(SYS_geteuid));
    601     }
    602 }
    603 
    604 pub fn getegid() u32 {
    605     if (@hasDecl(@This(), "SYS_getegid32")) {
    606         return @as(u32, syscall0(SYS_getegid32));
    607     } else {
    608         return @as(u32, syscall0(SYS_getegid));
    609     }
    610 }
    611 
    612 pub fn seteuid(euid: u32) usize {
    613     return setreuid(std.math.maxInt(u32), euid);
    614 }
    615 
    616 pub fn setegid(egid: u32) usize {
    617     return setregid(std.math.maxInt(u32), egid);
    618 }
    619 
    620 pub fn getresuid(ruid: *u32, euid: *u32, suid: *u32) usize {
    621     if (@hasDecl(@This(), "SYS_getresuid32")) {
    622         return syscall3(SYS_getresuid32, @ptrToInt(ruid), @ptrToInt(euid), @ptrToInt(suid));
    623     } else {
    624         return syscall3(SYS_getresuid, @ptrToInt(ruid), @ptrToInt(euid), @ptrToInt(suid));
    625     }
    626 }
    627 
    628 pub fn getresgid(rgid: *u32, egid: *u32, sgid: *u32) usize {
    629     if (@hasDecl(@This(), "SYS_getresgid32")) {
    630         return syscall3(SYS_getresgid32, @ptrToInt(rgid), @ptrToInt(egid), @ptrToInt(sgid));
    631     } else {
    632         return syscall3(SYS_getresgid, @ptrToInt(rgid), @ptrToInt(egid), @ptrToInt(sgid));
    633     }
    634 }
    635 
    636 pub fn setresuid(ruid: u32, euid: u32, suid: u32) usize {
    637     if (@hasDecl(@This(), "SYS_setresuid32")) {
    638         return syscall3(SYS_setresuid32, ruid, euid, suid);
    639     } else {
    640         return syscall3(SYS_setresuid, ruid, euid, suid);
    641     }
    642 }
    643 
    644 pub fn setresgid(rgid: u32, egid: u32, sgid: u32) usize {
    645     if (@hasDecl(@This(), "SYS_setresgid32")) {
    646         return syscall3(SYS_setresgid32, rgid, egid, sgid);
    647     } else {
    648         return syscall3(SYS_setresgid, rgid, egid, sgid);
    649     }
    650 }
    651 
    652 pub fn getgroups(size: usize, list: *u32) usize {
    653     if (@hasDecl(@This(), "SYS_getgroups32")) {
    654         return syscall2(SYS_getgroups32, size, @ptrToInt(list));
    655     } else {
    656         return syscall2(SYS_getgroups, size, @ptrToInt(list));
    657     }
    658 }
    659 
    660 pub fn setgroups(size: usize, list: *const u32) usize {
    661     if (@hasDecl(@This(), "SYS_setgroups32")) {
    662         return syscall2(SYS_setgroups32, size, @ptrToInt(list));
    663     } else {
    664         return syscall2(SYS_setgroups, size, @ptrToInt(list));
    665     }
    666 }
    667 
    668 pub fn getpid() pid_t {
    669     return @bitCast(pid_t, @truncate(u32, syscall0(SYS_getpid)));
    670 }
    671 
    672 pub fn gettid() pid_t {
    673     return @bitCast(pid_t, @truncate(u32, syscall0(SYS_gettid)));
    674 }
    675 
    676 pub fn sigprocmask(flags: u32, noalias set: ?*const sigset_t, noalias oldset: ?*sigset_t) usize {
    677     return syscall4(SYS_rt_sigprocmask, flags, @ptrToInt(set), @ptrToInt(oldset), NSIG / 8);
    678 }
    679 
    680 pub fn sigaction(sig: u6, noalias act: *const Sigaction, noalias oact: ?*Sigaction) usize {
    681     assert(sig >= 1);
    682     assert(sig != SIGKILL);
    683     assert(sig != SIGSTOP);
    684 
    685     const restorer_fn = if ((act.flags & SA_SIGINFO) != 0) restore_rt else restore;
    686     var ksa = k_sigaction{
    687         .sigaction = act.sigaction,
    688         .flags = act.flags | SA_RESTORER,
    689         .mask = undefined,
    690         .restorer = @ptrCast(extern fn () void, restorer_fn),
    691     };
    692     var ksa_old: k_sigaction = undefined;
    693     const ksa_mask_size = @sizeOf(@TypeOf(ksa_old.mask));
    694     @memcpy(@ptrCast([*]u8, &ksa.mask), @ptrCast([*]const u8, &act.mask), ksa_mask_size);
    695     const result = syscall4(SYS_rt_sigaction, sig, @ptrToInt(&ksa), @ptrToInt(&ksa_old), ksa_mask_size);
    696     const err = getErrno(result);
    697     if (err != 0) {
    698         return result;
    699     }
    700     if (oact) |old| {
    701         old.sigaction = ksa_old.sigaction;
    702         old.flags = @truncate(u32, ksa_old.flags);
    703         @memcpy(@ptrCast([*]u8, &old.mask), @ptrCast([*]const u8, &ksa_old.mask), ksa_mask_size);
    704     }
    705     return 0;
    706 }
    707 
    708 pub fn sigaddset(set: *sigset_t, sig: u6) void {
    709     const s = sig - 1;
    710     (set.*)[@intCast(usize, s) / usize.bit_count] |= @intCast(usize, 1) << (s & (usize.bit_count - 1));
    711 }
    712 
    713 pub fn sigismember(set: *const sigset_t, sig: u6) bool {
    714     const s = sig - 1;
    715     return ((set.*)[@intCast(usize, s) / usize.bit_count] & (@intCast(usize, 1) << (s & (usize.bit_count - 1)))) != 0;
    716 }
    717 
    718 pub fn getsockname(fd: i32, noalias addr: *sockaddr, noalias len: *socklen_t) usize {
    719     if (builtin.arch == .i386) {
    720         return socketcall(SC_getsockname, &[3]usize{ @bitCast(usize, @as(isize, fd)), @ptrToInt(addr), @ptrToInt(len) });
    721     }
    722     return syscall3(SYS_getsockname, @bitCast(usize, @as(isize, fd)), @ptrToInt(addr), @ptrToInt(len));
    723 }
    724 
    725 pub fn getpeername(fd: i32, noalias addr: *sockaddr, noalias len: *socklen_t) usize {
    726     if (builtin.arch == .i386) {
    727         return socketcall(SC_getpeername, &[3]usize{ @bitCast(usize, @as(isize, fd)), @ptrToInt(addr), @ptrToInt(len) });
    728     }
    729     return syscall3(SYS_getpeername, @bitCast(usize, @as(isize, fd)), @ptrToInt(addr), @ptrToInt(len));
    730 }
    731 
    732 pub fn socket(domain: u32, socket_type: u32, protocol: u32) usize {
    733     if (builtin.arch == .i386) {
    734         return socketcall(SC_socket, &[3]usize{ domain, socket_type, protocol });
    735     }
    736     return syscall3(SYS_socket, domain, socket_type, protocol);
    737 }
    738 
    739 pub fn setsockopt(fd: i32, level: u32, optname: u32, optval: [*]const u8, optlen: socklen_t) usize {
    740     if (builtin.arch == .i386) {
    741         return socketcall(SC_setsockopt, &[5]usize{ @bitCast(usize, @as(isize, fd)), level, optname, @ptrToInt(optval), @intCast(usize, optlen) });
    742     }
    743     return syscall5(SYS_setsockopt, @bitCast(usize, @as(isize, fd)), level, optname, @ptrToInt(optval), @intCast(usize, optlen));
    744 }
    745 
    746 pub fn getsockopt(fd: i32, level: u32, optname: u32, noalias optval: [*]u8, noalias optlen: *socklen_t) usize {
    747     if (builtin.arch == .i386) {
    748         return socketcall(SC_getsockopt, &[5]usize{ @bitCast(usize, @as(isize, fd)), level, optname, @ptrToInt(optval), @ptrToInt(optlen) });
    749     }
    750     return syscall5(SYS_getsockopt, @bitCast(usize, @as(isize, fd)), level, optname, @ptrToInt(optval), @ptrToInt(optlen));
    751 }
    752 
    753 pub fn sendmsg(fd: i32, msg: *msghdr_const, flags: u32) usize {
    754     if (builtin.arch == .i386) {
    755         return socketcall(SC_sendmsg, &[3]usize{ @bitCast(usize, @as(isize, fd)), @ptrToInt(msg), flags });
    756     }
    757     return syscall3(SYS_sendmsg, @bitCast(usize, @as(isize, fd)), @ptrToInt(msg), flags);
    758 }
    759 
    760 pub fn sendmmsg(fd: i32, msgvec: [*]mmsghdr_const, vlen: u32, flags: u32) usize {
    761     if (@typeInfo(usize).Int.bits > @typeInfo(@TypeOf(mmsghdr(undefined).msg_len)).Int.bits) {
    762         // workaround kernel brokenness:
    763         // if adding up all iov_len overflows a i32 then split into multiple calls
    764         // see https://www.openwall.com/lists/musl/2014/06/07/5
    765         const kvlen = if (vlen > IOV_MAX) IOV_MAX else vlen; // matches kernel
    766         var next_unsent: usize = 0;
    767         for (msgvec[0..kvlen]) |*msg, i| {
    768             var size: i32 = 0;
    769             const msg_iovlen = @intCast(usize, msg.msg_hdr.msg_iovlen); // kernel side this is treated as unsigned
    770             for (msg.msg_hdr.msg_iov[0..msg_iovlen]) |iov, j| {
    771                 if (iov.iov_len > std.math.maxInt(i32) or @addWithOverflow(i32, size, @intCast(i32, iov.iov_len), &size)) {
    772                     // batch-send all messages up to the current message
    773                     if (next_unsent < i) {
    774                         const batch_size = i - next_unsent;
    775                         const r = syscall4(SYS_sendmmsg, @bitCast(usize, @as(isize, fd)), @ptrToInt(&msgvec[next_unsent]), batch_size, flags);
    776                         if (getErrno(r) != 0) return next_unsent;
    777                         if (r < batch_size) return next_unsent + r;
    778                     }
    779                     // send current message as own packet
    780                     const r = sendmsg(fd, &msg.msg_hdr, flags);
    781                     if (getErrno(r) != 0) return r;
    782                     // Linux limits the total bytes sent by sendmsg to INT_MAX, so this cast is safe.
    783                     msg.msg_len = @intCast(u32, r);
    784                     next_unsent = i + 1;
    785                     break;
    786                 }
    787             }
    788         }
    789         if (next_unsent < kvlen or next_unsent == 0) { // want to make sure at least one syscall occurs (e.g. to trigger MSG_EOR)
    790             const batch_size = kvlen - next_unsent;
    791             const r = syscall4(SYS_sendmmsg, @bitCast(usize, @as(isize, fd)), @ptrToInt(&msgvec[next_unsent]), batch_size, flags);
    792             if (getErrno(r) != 0) return r;
    793             return next_unsent + r;
    794         }
    795         return kvlen;
    796     }
    797     return syscall4(SYS_sendmmsg, @bitCast(usize, @as(isize, fd)), @ptrToInt(msgvec), vlen, flags);
    798 }
    799 
    800 pub fn connect(fd: i32, addr: *const c_void, len: socklen_t) usize {
    801     if (builtin.arch == .i386) {
    802         return socketcall(SC_connect, &[3]usize{ @bitCast(usize, @as(isize, fd)), @ptrToInt(addr), len });
    803     }
    804     return syscall3(SYS_connect, @bitCast(usize, @as(isize, fd)), @ptrToInt(addr), len);
    805 }
    806 
    807 pub fn recvmsg(fd: i32, msg: *msghdr, flags: u32) usize {
    808     if (builtin.arch == .i386) {
    809         return socketcall(SC_recvmsg, &[3]usize{ @bitCast(usize, @as(isize, fd)), @ptrToInt(msg), flags });
    810     }
    811     return syscall3(SYS_recvmsg, @bitCast(usize, @as(isize, fd)), @ptrToInt(msg), flags);
    812 }
    813 
    814 pub fn recvfrom(fd: i32, noalias buf: [*]u8, len: usize, flags: u32, noalias addr: ?*sockaddr, noalias alen: ?*socklen_t) usize {
    815     if (builtin.arch == .i386) {
    816         return socketcall(SC_recvfrom, &[6]usize{ @bitCast(usize, @as(isize, fd)), @ptrToInt(buf), len, flags, @ptrToInt(addr), @ptrToInt(alen) });
    817     }
    818     return syscall6(SYS_recvfrom, @bitCast(usize, @as(isize, fd)), @ptrToInt(buf), len, flags, @ptrToInt(addr), @ptrToInt(alen));
    819 }
    820 
    821 pub fn shutdown(fd: i32, how: i32) usize {
    822     if (builtin.arch == .i386) {
    823         return socketcall(SC_shutdown, &[2]usize{ @bitCast(usize, @as(isize, fd)), @bitCast(usize, @as(isize, how)) });
    824     }
    825     return syscall2(SYS_shutdown, @bitCast(usize, @as(isize, fd)), @bitCast(usize, @as(isize, how)));
    826 }
    827 
    828 pub fn bind(fd: i32, addr: *const sockaddr, len: socklen_t) usize {
    829     if (builtin.arch == .i386) {
    830         return socketcall(SC_bind, &[3]usize{ @bitCast(usize, @as(isize, fd)), @ptrToInt(addr), @intCast(usize, len) });
    831     }
    832     return syscall3(SYS_bind, @bitCast(usize, @as(isize, fd)), @ptrToInt(addr), @intCast(usize, len));
    833 }
    834 
    835 pub fn listen(fd: i32, backlog: u32) usize {
    836     if (builtin.arch == .i386) {
    837         return socketcall(SC_listen, &[2]usize{ @bitCast(usize, @as(isize, fd)), backlog });
    838     }
    839     return syscall2(SYS_listen, @bitCast(usize, @as(isize, fd)), backlog);
    840 }
    841 
    842 pub fn sendto(fd: i32, buf: [*]const u8, len: usize, flags: u32, addr: ?*const sockaddr, alen: socklen_t) usize {
    843     if (builtin.arch == .i386) {
    844         return socketcall(SC_sendto, &[6]usize{ @bitCast(usize, @as(isize, fd)), @ptrToInt(buf), len, flags, @ptrToInt(addr), @intCast(usize, alen) });
    845     }
    846     return syscall6(SYS_sendto, @bitCast(usize, @as(isize, fd)), @ptrToInt(buf), len, flags, @ptrToInt(addr), @intCast(usize, alen));
    847 }
    848 
    849 pub fn socketpair(domain: i32, socket_type: i32, protocol: i32, fd: [2]i32) usize {
    850     if (builtin.arch == .i386) {
    851         return socketcall(SC_socketpair, &[4]usize{ @intCast(usize, domain), @intCast(usize, socket_type), @intCast(usize, protocol), @ptrToInt(&fd[0]) });
    852     }
    853     return syscall4(SYS_socketpair, @intCast(usize, domain), @intCast(usize, socket_type), @intCast(usize, protocol), @ptrToInt(&fd[0]));
    854 }
    855 
    856 pub fn accept(fd: i32, noalias addr: *sockaddr, noalias len: *socklen_t) usize {
    857     if (builtin.arch == .i386) {
    858         return socketcall(SC_accept, &[4]usize{ fd, addr, len, 0 });
    859     }
    860     return accept4(fd, addr, len, 0);
    861 }
    862 
    863 pub fn accept4(fd: i32, noalias addr: *sockaddr, noalias len: *socklen_t, flags: u32) usize {
    864     if (builtin.arch == .i386) {
    865         return socketcall(SC_accept4, &[4]usize{ @bitCast(usize, @as(isize, fd)), @ptrToInt(addr), @ptrToInt(len), flags });
    866     }
    867     return syscall4(SYS_accept4, @bitCast(usize, @as(isize, fd)), @ptrToInt(addr), @ptrToInt(len), flags);
    868 }
    869 
    870 pub fn fstat(fd: i32, stat_buf: *Stat) usize {
    871     if (@hasDecl(@This(), "SYS_fstat64")) {
    872         return syscall2(SYS_fstat64, @bitCast(usize, @as(isize, fd)), @ptrToInt(stat_buf));
    873     } else {
    874         return syscall2(SYS_fstat, @bitCast(usize, @as(isize, fd)), @ptrToInt(stat_buf));
    875     }
    876 }
    877 
    878 pub fn stat(pathname: [*:0]const u8, statbuf: *Stat) usize {
    879     if (@hasDecl(@This(), "SYS_stat64")) {
    880         return syscall2(SYS_stat64, @ptrToInt(pathname), @ptrToInt(statbuf));
    881     } else {
    882         return syscall2(SYS_stat, @ptrToInt(pathname), @ptrToInt(statbuf));
    883     }
    884 }
    885 
    886 pub fn lstat(pathname: [*:0]const u8, statbuf: *Stat) usize {
    887     if (@hasDecl(@This(), "SYS_lstat64")) {
    888         return syscall2(SYS_lstat64, @ptrToInt(pathname), @ptrToInt(statbuf));
    889     } else {
    890         return syscall2(SYS_lstat, @ptrToInt(pathname), @ptrToInt(statbuf));
    891     }
    892 }
    893 
    894 pub fn fstatat(dirfd: i32, path: [*:0]const u8, stat_buf: *Stat, flags: u32) usize {
    895     if (@hasDecl(@This(), "SYS_fstatat64")) {
    896         return syscall4(SYS_fstatat64, @bitCast(usize, @as(isize, dirfd)), @ptrToInt(path), @ptrToInt(stat_buf), flags);
    897     } else {
    898         return syscall4(SYS_fstatat, @bitCast(usize, @as(isize, dirfd)), @ptrToInt(path), @ptrToInt(stat_buf), flags);
    899     }
    900 }
    901 
    902 pub fn statx(dirfd: i32, path: [*]const u8, flags: u32, mask: u32, statx_buf: *Statx) usize {
    903     if (@hasDecl(@This(), "SYS_statx")) {
    904         return syscall5(
    905             SYS_statx,
    906             @bitCast(usize, @as(isize, dirfd)),
    907             @ptrToInt(path),
    908             flags,
    909             mask,
    910             @ptrToInt(statx_buf),
    911         );
    912     }
    913     return @bitCast(usize, @as(isize, -ENOSYS));
    914 }
    915 
    916 pub fn listxattr(path: [*:0]const u8, list: [*]u8, size: usize) usize {
    917     return syscall3(SYS_listxattr, @ptrToInt(path), @ptrToInt(list), size);
    918 }
    919 
    920 pub fn llistxattr(path: [*:0]const u8, list: [*]u8, size: usize) usize {
    921     return syscall3(SYS_llistxattr, @ptrToInt(path), @ptrToInt(list), size);
    922 }
    923 
    924 pub fn flistxattr(fd: usize, list: [*]u8, size: usize) usize {
    925     return syscall3(SYS_flistxattr, fd, @ptrToInt(list), size);
    926 }
    927 
    928 pub fn getxattr(path: [*:0]const u8, name: [*:0]const u8, value: [*]u8, size: usize) usize {
    929     return syscall4(SYS_getxattr, @ptrToInt(path), @ptrToInt(name), @ptrToInt(value), size);
    930 }
    931 
    932 pub fn lgetxattr(path: [*:0]const u8, name: [*:0]const u8, value: [*]u8, size: usize) usize {
    933     return syscall4(SYS_lgetxattr, @ptrToInt(path), @ptrToInt(name), @ptrToInt(value), size);
    934 }
    935 
    936 pub fn fgetxattr(fd: usize, name: [*:0]const u8, value: [*]u8, size: usize) usize {
    937     return syscall4(SYS_lgetxattr, fd, @ptrToInt(name), @ptrToInt(value), size);
    938 }
    939 
    940 pub fn setxattr(path: [*:0]const u8, name: [*:0]const u8, value: *const void, size: usize, flags: usize) usize {
    941     return syscall5(SYS_setxattr, @ptrToInt(path), @ptrToInt(name), @ptrToInt(value), size, flags);
    942 }
    943 
    944 pub fn lsetxattr(path: [*:0]const u8, name: [*:0]const u8, value: *const void, size: usize, flags: usize) usize {
    945     return syscall5(SYS_lsetxattr, @ptrToInt(path), @ptrToInt(name), @ptrToInt(value), size, flags);
    946 }
    947 
    948 pub fn fsetxattr(fd: usize, name: [*:0]const u8, value: *const void, size: usize, flags: usize) usize {
    949     return syscall5(SYS_fsetxattr, fd, @ptrToInt(name), @ptrToInt(value), size, flags);
    950 }
    951 
    952 pub fn removexattr(path: [*:0]const u8, name: [*:0]const u8) usize {
    953     return syscall2(SYS_removexattr, @ptrToInt(path), @ptrToInt(name));
    954 }
    955 
    956 pub fn lremovexattr(path: [*:0]const u8, name: [*:0]const u8) usize {
    957     return syscall2(SYS_lremovexattr, @ptrToInt(path), @ptrToInt(name));
    958 }
    959 
    960 pub fn fremovexattr(fd: usize, name: [*:0]const u8) usize {
    961     return syscall2(SYS_fremovexattr, fd, @ptrToInt(name));
    962 }
    963 
    964 pub fn sched_yield() usize {
    965     return syscall0(SYS_sched_yield);
    966 }
    967 
    968 pub fn sched_getaffinity(pid: pid_t, size: usize, set: *cpu_set_t) usize {
    969     const rc = syscall3(SYS_sched_getaffinity, @bitCast(usize, @as(isize, pid)), size, @ptrToInt(set));
    970     if (@bitCast(isize, rc) < 0) return rc;
    971     if (rc < size) @memset(@ptrCast([*]u8, set) + rc, 0, size - rc);
    972     return 0;
    973 }
    974 
    975 pub fn epoll_create() usize {
    976     return epoll_create1(0);
    977 }
    978 
    979 pub fn epoll_create1(flags: usize) usize {
    980     return syscall1(SYS_epoll_create1, flags);
    981 }
    982 
    983 pub fn epoll_ctl(epoll_fd: i32, op: u32, fd: i32, ev: ?*epoll_event) usize {
    984     return syscall4(SYS_epoll_ctl, @bitCast(usize, @as(isize, epoll_fd)), @intCast(usize, op), @bitCast(usize, @as(isize, fd)), @ptrToInt(ev));
    985 }
    986 
    987 pub fn epoll_wait(epoll_fd: i32, events: [*]epoll_event, maxevents: u32, timeout: i32) usize {
    988     return epoll_pwait(epoll_fd, events, maxevents, timeout, null);
    989 }
    990 
    991 pub fn epoll_pwait(epoll_fd: i32, events: [*]epoll_event, maxevents: u32, timeout: i32, sigmask: ?*sigset_t) usize {
    992     return syscall6(
    993         SYS_epoll_pwait,
    994         @bitCast(usize, @as(isize, epoll_fd)),
    995         @ptrToInt(events),
    996         @intCast(usize, maxevents),
    997         @bitCast(usize, @as(isize, timeout)),
    998         @ptrToInt(sigmask),
    999         @sizeOf(sigset_t),
   1000     );
   1001 }
   1002 
   1003 pub fn eventfd(count: u32, flags: u32) usize {
   1004     return syscall2(SYS_eventfd2, count, flags);
   1005 }
   1006 
   1007 pub fn timerfd_create(clockid: i32, flags: u32) usize {
   1008     return syscall2(SYS_timerfd_create, @bitCast(usize, @as(isize, clockid)), flags);
   1009 }
   1010 
   1011 pub const itimerspec = extern struct {
   1012     it_interval: timespec,
   1013     it_value: timespec,
   1014 };
   1015 
   1016 pub fn timerfd_gettime(fd: i32, curr_value: *itimerspec) usize {
   1017     return syscall2(SYS_timerfd_gettime, @bitCast(usize, @as(isize, fd)), @ptrToInt(curr_value));
   1018 }
   1019 
   1020 pub fn timerfd_settime(fd: i32, flags: u32, new_value: *const itimerspec, old_value: ?*itimerspec) usize {
   1021     return syscall4(SYS_timerfd_settime, @bitCast(usize, @as(isize, fd)), flags, @ptrToInt(new_value), @ptrToInt(old_value));
   1022 }
   1023 
   1024 pub fn unshare(flags: usize) usize {
   1025     return syscall1(SYS_unshare, flags);
   1026 }
   1027 
   1028 pub fn capget(hdrp: *cap_user_header_t, datap: *cap_user_data_t) usize {
   1029     return syscall2(SYS_capget, @ptrToInt(hdrp), @ptrToInt(datap));
   1030 }
   1031 
   1032 pub fn capset(hdrp: *cap_user_header_t, datap: *const cap_user_data_t) usize {
   1033     return syscall2(SYS_capset, @ptrToInt(hdrp), @ptrToInt(datap));
   1034 }
   1035 
   1036 pub fn sigaltstack(ss: ?*stack_t, old_ss: ?*stack_t) usize {
   1037     return syscall2(SYS_sigaltstack, @ptrToInt(ss), @ptrToInt(old_ss));
   1038 }
   1039 
   1040 pub fn uname(uts: *utsname) usize {
   1041     return syscall1(SYS_uname, @ptrToInt(uts));
   1042 }
   1043 
   1044 // XXX: This should be weak
   1045 extern const __ehdr_start: elf.Ehdr = undefined;
   1046 
   1047 pub fn dl_iterate_phdr(comptime T: type, callback: extern fn (info: *dl_phdr_info, size: usize, data: ?*T) i32, data: ?*T) isize {
   1048     if (builtin.link_libc) {
   1049         return std.c.dl_iterate_phdr(@ptrCast(std.c.dl_iterate_phdr_callback, callback), @ptrCast(?*c_void, data));
   1050     }
   1051 
   1052     const elf_base = @ptrToInt(&__ehdr_start);
   1053     const n_phdr = __ehdr_start.e_phnum;
   1054     const phdrs = (@intToPtr([*]elf.Phdr, elf_base + __ehdr_start.e_phoff))[0..n_phdr];
   1055 
   1056     var it = dl.linkmap_iterator(phdrs) catch return 0;
   1057 
   1058     // The executable has no dynamic link segment, create a single entry for
   1059     // the whole ELF image
   1060     if (it.end()) {
   1061         var info = dl_phdr_info{
   1062             .dlpi_addr = elf_base,
   1063             .dlpi_name = "/proc/self/exe",
   1064             .dlpi_phdr = @intToPtr([*]elf.Phdr, elf_base + __ehdr_start.e_phoff),
   1065             .dlpi_phnum = __ehdr_start.e_phnum,
   1066         };
   1067 
   1068         return callback(&info, @sizeOf(dl_phdr_info), data);
   1069     }
   1070 
   1071     // Last return value from the callback function
   1072     var last_r: isize = 0;
   1073     while (it.next()) |entry| {
   1074         var dlpi_phdr: usize = undefined;
   1075         var dlpi_phnum: u16 = undefined;
   1076 
   1077         if (entry.l_addr != 0) {
   1078             const elf_header = @intToPtr(*elf.Ehdr, entry.l_addr);
   1079             dlpi_phdr = entry.l_addr + elf_header.e_phoff;
   1080             dlpi_phnum = elf_header.e_phnum;
   1081         } else {
   1082             // This is the running ELF image
   1083             dlpi_phdr = elf_base + __ehdr_start.e_phoff;
   1084             dlpi_phnum = __ehdr_start.e_phnum;
   1085         }
   1086 
   1087         var info = dl_phdr_info{
   1088             .dlpi_addr = entry.l_addr,
   1089             .dlpi_name = entry.l_name,
   1090             .dlpi_phdr = @intToPtr([*]elf.Phdr, dlpi_phdr),
   1091             .dlpi_phnum = dlpi_phnum,
   1092         };
   1093 
   1094         last_r = callback(&info, @sizeOf(dl_phdr_info), data);
   1095         if (last_r != 0) break;
   1096     }
   1097 
   1098     return last_r;
   1099 }
   1100 
   1101 pub fn io_uring_setup(entries: u32, p: *io_uring_params) usize {
   1102     return syscall2(SYS_io_uring_setup, entries, @ptrToInt(p));
   1103 }
   1104 
   1105 pub fn io_uring_enter(fd: i32, to_submit: u32, min_complete: u32, flags: u32, sig: ?*sigset_t) usize {
   1106     return syscall6(SYS_io_uring_enter, @bitCast(usize, @as(isize, fd)), to_submit, min_complete, flags, @ptrToInt(sig), NSIG / 8);
   1107 }
   1108 
   1109 pub fn io_uring_register(fd: i32, opcode: u32, arg: ?*const c_void, nr_args: u32) usize {
   1110     return syscall4(SYS_io_uring_register, @bitCast(usize, @as(isize, fd)), opcode, @ptrToInt(arg), nr_args);
   1111 }
   1112 
   1113 pub fn memfd_create(name: [*:0]const u8, flags: u32) usize {
   1114     return syscall2(SYS_memfd_create, @ptrToInt(name), flags);
   1115 }
   1116 
   1117 test "" {
   1118     if (builtin.os == .linux) {
   1119         _ = @import("linux/test.zig");
   1120     }
   1121 }